This invention relates to lubricants for and methods of processing synthetic fibers
During the spinning process of synthetic fibers such as polyamide and polyester fibers, it is important to prevent generation of fuzz and occurrence of yarn breakages. Since synthetic fibers for industrial materials such as tire cords, seat belts and air bags are produced under severe conditions of high temperature and high contact pressure and are likely to generate fuzz and yarn breakages, it is particularly important with such fibers to prevent generation of fuzz and occurrence of yarn breakages. Agents for lubricating such synthetic fibers (herein referred to simply as the lubricants) are therefore required to be capable of providing sufficient lubricity even to such synthetic fibers adapted to undergo a spinning process under a condition of high temperature and high contact pressure. This invention relates to lubricating agents which can respond to such a demand and also to methods of processing synthetic fibers.
Examples of prior art lubricant proposed for providing lubricity even to synthetic fibers adapted to undergo a spinning process under a severe condition of high temperature and high contact pressure include (1) polyester obtained from polyhydroxy compound and dibasic acid having its end closed with aliphatic alcohol, its alkylene oxide adduct or aliphatic carboxylic acid (Japanese Patent Publications Tokkai 3-871 and 5-339875), (2) polyoxyalkyleneglycol with numerically averaged molecular weight greater than 1000 (Japanese Patent Publication Tokkai 6-158538), (3) nitrogenous compounds of numerically averaged molecular weight 1000-20000 obtained by adding alkylene oxide to aliphatic amine (Japanese Patent Publication Tokkai 6-228885), (4) metallic salt of phosphoro-dithioate such as zinc di(di n-butyl phosphoro-dithioate) (U.S. Pat. No. 5,269,950), and (5) silane compound containing mercapto group such as .gamma.-mercaptopropyl trimethoxy silane (U.S. Pat. No. 5,269,950). These prior art lubricants cannot provide a high level of lubricity to synthetic fibers, however, and lubricity can be provided only to a very unsatisfactory level in the case of synthetic fibers as industrial materials adapted to be processed under a condition of high temperature and high contact pressure. Thus, the generation of fuzz and occurrence of yarn breakage could not be adequately prevented by prior art lubricants.